PRISM and related programs may harvest metadata of every phone call, every email, every Internet search, every Facebook post -- everything -- and use algorithmic filtering to find suspicious communication. Once they've found it, they can get a warrant to listen to the actual phone calls and read the actual email to find clues that enable authorities to stop terrorist attacks before they happen. (You know, Minority Report-style precrime.)

Metadata is not the content of the phone call or email, but the information about them: Who contacted whom, when, from where and for how long.

PRISM inspires shock and awe. But if you set aside the shock part -- the privacy and constitutional implications -- you realize the awe component is worth exploring.

The PRISM approach is this: Cast the widest possible information net, then use machine intelligence to serve up just the needles without the haystack.

Google also offers an Alerts service that searches the Internet and mails you the results. Most people set up only the number of Alerts that they can read. But that's not the NSA way.

The PRISM approach would be to harvest far more Google Alerts than any human could possible process, then use Gmail filters to automatically skip the inbox and send them straight to a specially created folder within Gmail. You can set up new Alerts every day each time you think of an area of interest. These can include people you know, companies to watch, ideas to keep up with.

Alerts won't send you the data (the story), but the metadata (information about the story, plus the link). One advantage of this approach is that if a site is deleted, making it vanish also from Google Search, you'll still have a record of it with enough metadata to pursue leads.